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where, by the action of tRNA, amino acids are finally

formed into proteins (Figure 4). The control of the

activities of genes at the cellular level is summarised in

Figure 5.

There are numerous codes stored on a DNA

strand. Without an efficient control of gene activities the

system would not work. One of the major control

mechanisms related to epigenetic is linked to DNA

methylation. A methyl group at the 5

th

carbon of the

cytosine base is added into a CpG dinucleotide pair

(Figure 6). Transcription along a DNA strand is

initiated by a promoter which enables transcription.

Chromatin, which is genomic DNA in

eukaryotic cells, is attached together with proteins

named histones, located within the cell’s nucleolus,

interacts with the promoter to reduce

transcription and, in a highly methylated

state, heterochromatin is silenced.

Epigenetic phenomena also can

be triggered by chromatin remodeling. In

this case, an originally blocked promoter

region is freed up for transcription

because specific nucleosomes (Figure 7)

act at times of cell differentiations and

developments.

How epigenetic works is not yet

entirely clear and what is known is much more complex

than is described here. However, to go deeper into the

molecular and genetic mechanisms is beyond the aim

this article, which is intended just to give a broad

overview of what epigenetic is all about and why public

health academics should be interested in the topic.

When it comes to T2DM and obesity, it is still

true that major risk factors are a sedative life style and an oversupply of energy intake,

particularly in the form of carbohydrates. Recent interest in the genetic background of T2DM

and obesity has so far revealed about 150 genetic loci, but only 5 – 10% of the variance in the

development of T2DM and obesity has been attributed to genetic loci and only about to 2% of

the variance in body mass index (BMI).

Fig.: 4 Control of activities of

genes at the cellular level

( http://en.wikipedia.org/wiki/File

:

Gene_expression_control.png/

retr.: 21.02.2014)

Fig.: 4 Control of activities of

genes at the cellular level

( http://en.wikipedia.org/wiki/File

:

Gene_expression_control.png/

retr.: 21.02.2014)